As a method for producing a lens array having a resin transfer layer provided on a substrate, there exists one that forms a concave part so as to surround each transfer part provided in a molding mold and prevents transfer material from spreading around. Specifically, the resin is prevented from spreading outward by providing a buffer part which is a hollow around a ring-band shaped spacer part surrounding a cavity part for transfer, and also a resin confinement structure of an edge or a groove is provided in the spacer part (refer to patent literature 1). For reference, FIGS. 1 and 2 in patent literature 1 are attached in FIG. 14.
In another example, a spacer part having a small spacing is provided around an element capacitance part, and also an overflow part having a large spacing is provided thereoutside to allow resin to flow to the overflow part having the large spacing, and thereby the spread of the resin is prevented (refer to patent literature 2). For reference, FIG. 1 in patent literature 2 is attached in FIG. 15.
In a method for producing a lens array as described above, since a ring-shaped spacer part is provided so as to surround a cavity part, when resin which has run over around the spacer part spreads along the periphery of the spacer part and contacts the resin from the opposite side, the resin create a weld to trap air bubbles. Further, a buffer part or an overflow part around the spacer part, and a transfer mold for providing these parts, are a hollow that needs to be formed by machining work using a cutting tool such as an end mill, and a long time is required for the work of the transfer mold. In particular, as a lens of the lens array becomes smaller and the lens array is more highly integrated, the buffer part becomes also smaller and the work time of the transfer mold is increased considerably.